[PATCH] ELF: emit symbol table when there are relocations

[Jan Beulich]

Even when there are no symbols (e.g. all relocations being against
absolute values), a symbol table (with just the first placeholder entry)
needs to be emitted. Otherwise tools like objdump won't properly process
the relocations. The respective checks in assign_section_numbers() and
_bfd_elf_compute_section_file_positions() support also this view. Oddly
enough so far HAS_RELOC was only set when reading in an object file, but
not when generating one anew; the flag would only have been cleared when
no relocations were found (anymore).

While there also amend the affected function's leading comment to also
mention gas.
---
I'm not adding a testcase as I don't see a good way to. The involved
relocations are target specific, and hence in principle one test per
target would be needed for sufficient coverage. I could drop the label
again in an x86-64 test I'm soon to submit, which is where I did
actually notice the issue (leading to me adding a label there to have a
non-empty symbol table).

--- a/bfd/elf.c
+++ b/bfd/elf.c
@@ -3674,7 +3674,7 @@ elf_get_reloc_section (asection *reloc_s
 /* Assign all ELF section numbers.  The dummy first section is handled here
    too.  The link/info pointers for the standard section types are filled
    in here too, while we're at it.  LINK_INFO will be 0 when arriving
-   here for objcopy, and when using the generic ELF linker.  */
+   here for gas, objcopy, and when using the generic ELF linker.  */
 
 static bool
 assign_section_numbers (bfd *abfd, struct bfd_link_info *link_info)
@@ -3717,9 +3717,11 @@ assign_section_numbers (bfd *abfd, struc
 	  reloc_count += sec->reloc_count;
 	}
 
-      /* Clear HAS_RELOC if there are no relocations.  */
+      /* Set/clear HAS_RELOC depending on whether there are relocations.  */
       if (reloc_count == 0)
 	abfd->flags &= ~HAS_RELOC;
+      else
+	abfd->flags |= HAS_RELOC;
     }
 
   for (sec = abfd->sections; sec; sec = sec->next)